Metallurgy of zinc.



s SHEETS-SHEET 1.

Patented June 25, 1912 C. V. THIERRY.

METALLURGY OP ZINC.

APPLICATION FILED 00Ty s, 1911.

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C. V. THIERRY.

MBTALLURGY OP ZINC.

APPLICATION FILED 0016;,1911,

Patented Junev25, 1912.

S SHEETS-SHEET 2.

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C. V. THIERRY.

METALLURGY OP ZINC.

APPLICATION FILED 00T. 1911.

PatentedJune 25, 1912.

3 SHEETS-SHEET 3.

INI/ENTOH MTM? /J/J A NORA/EVS CHARLES V. THIERRY, OF PARIS, FRANCE.

METALLURGY 0F ZINC.

Specification of Letters Patent, Patented June 25, jitif..

Application filed October -6, 1911. Serial No. 653,249.

To all whom it may concern Be it known that I, CHARLES V.TH IERRY, a citizen of the Republic of France, and a residentof the city .of Paris, in said Republic of France, have invented certain new and useful Improvements Relating to the Metallurgy of Zinc, of which the following is a specification.

This inventionrelates to the metallurgy of zinc and the object thereof is to produce metallic zinc' by the reduction of oXid-ofzinc (ZnG) by carbon (C) the heat necesfor such'decompos'ition being derived from an electric current passed through a resistor in the form of a bed of broken carbon.

The invention also relates to the manufacture of zinc from the oXid-of-zinc by reducing the oXid by and in the presence of heated carbon, thereby producing fumes of zinc, and subsequently vcondensing said fumes toliquid zinc by retaining the fumes in the presence of carbon' until the zinc 'fumes have been condensed.

rlhe invention Jfurthermore relates to apparatus particularly adapted for and designed to accomplish the above in a practical, eifective and commercial manner.

ln general terms, the resistor, above re ferred to, is comprised in a bed of carbon, usually made of colte, loosely disposed upon a refractory hearth and confined by sidewalls, the inner half of which is preferably of the same material, e'. e., carbon. The size and shape of the carbon pieces vin the resistor as well as the depth, width and length of the resistor bed may be variously modified to obtain any electrical resistance and intensity of currentwhich may be desired; but the pieces ordinarily used are from about to inch diameter. rentis brought to the two ends of the resistor by blocks or rods of amorphousI carbon or graphite which pass throughsuitably tamped lioints in the end-walls of the furnace, that is the resistor is interpolated between the two terminals. It will be evident that the refractory material used 1n the construction of the chamber or channel that contains the resistor should be a poor conductor of electricit-yrwhereby to avoid current leakage and useless dissipation of energy. The reaction and resistor chamber of the furnace is made ofsuficient depth to also receive the charge; which is placed The curd irectly upon and is sustained by the resistor.

The charge in its entirety is either a mixture or alternate layers of oxid-of-iniA and of carbon in preferably the exact rela tive proportions to effect, when suitabiyr heated, their complete reduction.

A's has already been intimated, the electric energy is trai. 'formed into caloric energy .in the resistor-bed; 'the heatvthus generated effects the decomposition of thesuperimposed mass and the following chemical reaction ensues:

zno-i-ozzmfco.

As a consequence of the foregoing conditions, the charged material is evolved in gaseous forms. Thus, on the one hand, fumes-of-zinc, and, on the other hand, oxidof-carbon, are produced. The zinc-fumes, together with the oxid-of-carbon, or any other entrained gases, esc-ape through a suitable opening, or openings, in the furnace walls into a condenser, or condensers, where the Zinc fumes (Zn) condense in a metallic form and the oxidof-carbon (CO) mingles Awith the atmosphere or is burned.

To obtain zinc as a fluid metal, it is essential that the condenser, or condensers`r shall be maintained by some suitable method and means at the proper thermal conditions. In fact, the temperature of' av condenser should progressively decrease, Afrom the entry-end to the other, falling from about 9509 to 450 C.; but no portion of a con' denser should be lower than somewluil above the temperature of the melting p int of zinc, on say about 420 C. as a minimum. This condition may be etilectually obtained by control of the radiated heat and also by externally heating the eondenser. Again, to avoid a secondary oxidization of the zinc-fumes, as by such gases as CO2, H2O, etc., they should be kept eontinuously in a reducing medium; the gases escaping from the furnace should, as it were, be filtered and t-he condensing surface be as great as possible. A

An example or embodiment of my invention is shown in the accompanying drawings in which,

Figure l is a vert-icaltransverse section of the furnace and its condensers, as on the line A ofyFig; lFig. 2 is a horizontal section to the longitudinal center line, he remainder, partially broken off, being in plan, and Fig. 3 is a side elevation, a series of the condensers being omitted 0n the right hand side to show the aperture in the furnace wall into which the necks of the eondensers are cemented..

l B is the' reaction chamber on whose bottom, or hearth. 5, is placed the bed of earbon which constitutes' the resistor C, its ends being in contact with theterminals or electrodes, (3, 7 which convey the current t0 the resistor, as from the power circuit D. The chamber is closed by a cover, or covers, E.` Openings, as F, are formed in the side walls of the chamber, which receive the inlet ends, 8, of the condensers, The condensers as here shown are of trapezoidal form in vertical longitudinal section; the upper portion, 9, being set horizontal so as to give a suitable slope on the lower surface, l0, for the flow of the condensed zinc. The smaller, or inlet, ends of the condensers are setand secured into the furnace openingsvlf by a tamped joint, but their faces only penetrate to about the middle of the thickness of the furnace walls or to the point where the carbon portions of the side walls begin. The large, or outer, ends of the condenser-s are closed by plugs 0f refractory material, as ll, having a. vent, l2, for the escape of CO, while the tap hole, 13, at the bottom, is for drawing` ott Izinc.

If itis desired to make lalue-powcle1", then the ordinary balloons as I, are connected to the vent-openings, l2, in which instance. the It) and other lixed ,frases pass therein and therethrough and are burned as Shown at. lt.

ln thepresent illustration, there are four furnace openings, F, each adapted to receive six condensers, that is twelve on each side, or twenty-four in all. 4rl`he condenscrs are iuclosed in chambers. S, 'l`,.formcd of brick work, and under each series of condensers is a grate 14, upon which charcoal, coke or coal may be burned, when retpiired, to increase the temperature within the chambers. Naturally, this heating may be obtained in any other appropriate manner, as by means of gas or a resistor acted upon electrically.

Receptacles, as K, may be placed in the top or roof of the condenser chambers, whereby to receive the oxid-of-Zinc, or a mixture of theI oxid-and carbon, for the purpose of pre-heatiur the same by utilization of a portion of the heat radiated -by the condensers or generated by the grate-tire. 'lhese receptacles may be conveniently inclosed, as by the covers l5. lhe furnace cover is provided with a series of openings, disposed above the reaction clnunber, in which are placed feed-tunnels. lo, ordinarily closed by means of plugs, aslT.

In the. primary assemblage of the furnace,

the longitudinal portions in front of the ol'iei'lings F, of the inner ends of the condensers, and also the interiors of the condensers themselves, are. packed with large piecesof carbon, as lS, and the carbon for forming the. resistor-bed is then placed in the channel, resting upon the bottom, or

hearth, of the chamber. The paeks'of carbon 'which are located upon the opposite sides of the furnace in the longitudinal portions above referred to, really constitute and form the inner halves of, or at least the linings for, the side walls of the furnace.

AThe operation of the furnace is as followsz--The resistor preferably having,r been brought by the passage of electric current to the desired temperature, say about 12000 to 13000 C., a composite charge of oXid-efzinc and of carbon, as M, is applied directly upon the upper 'surface of the resistor. lt should be noted however that the chamberv may be charged before switching;r on the currentor when the resistor isonly partially` heated. Thethickness or depth of the charge should be sufficient to prevent the zinc fumes and oXid-of-carbon from passing` up there-` through. '.lhis also avoids excessive radiation ot heat from the top of the charge. On the other hand, the charge should not be .so deep and heavy'as to sensibly diminish, by. its pressure and conductivity, the electrical resistance of the underlying resistor.

rl`he reaction Zitti-{ t-:Zn-l-CO,

takes place principally where the charged mixture impinges upon the resistor. rlhe zone of reaction, however, extends sfnnewhat upwardly into the charge anc also perhaps along the sides of the resistor, that is somewhat in the carbon packed within the aforesaid furnace-chambcr spaces or in the carbon foi-mitrey the inner portions of the side walls. But the height of the reaction within the mixture ot ord and carbon main-- tained practically ccnsiaut by successive recharging's, the frequenov andY quantity ot' which depend upon the rapidity of the reaction.

However anomalous it may appear as related to a Zinc furnace. it is yet a matter ot' fact that. when a fairly constant. depth of charge is mai-ntained, the furnace may be operated without coverimgy the. reaction chamber: Nevertheless, the presence of a cover is'preferable and has a distinct utility when it is desired to visually examine the lreaction chamber and to expose the upper surface of the resistor, as before this can be done the charge must be allowed to completely exhaust itself.

The funnels in the cover provide a. convenient means of charging;` and also, by rods or bars, to spread the same if necessary. i loreover, they can be utilized as peep-hotes.

i approaching However, the feeding intervals are best de noted by a voltlmeter; tor when a charge is exhaustion this sulliciently aiects the normal resistance to serve as an indication that additional material is required.

A It will now be seen that the fumes and l self; thence through the packed carbon in the sides and finally into the interstitial spaces termed by the carbon contained within the condensers. Consetpiently. from the instant when the r/.inc is gaseously evolved until precipitated as liquid metal it must necessarily and continuously flow in a path obstructed by a reducing medium.

The condensiiipl Zone begins at, or near to, tpe inlets ot' the condensers and this zone continues outwardly, but with a progressively decreasing temperature, until the liquid zinc Z, is collected at the front ends, along the lower surfaces, as indicated.

ln lirst putting the furnace into operation it is advantageous to pre-heat the condensers to a proper temperature, which is well at` tained by in eans ot the fuel-tired grates, 14. rlhen by constructing the outer walls, as l), ot the condenser chambers comparatively thin, whereby to realize a rapid and tree radiation ot' heat trom the ends` ot the con densers farthest from the furnace, it becomes an easy matter, by manipulation ot' the tire, and also ot the stolieopenings, as N, to prevent the temperature troni becoming either too high or too low.

i rhere is an advantage ot considerable practical importance in having the condens- ,ers in parallel batteries on the right and lett hand sides ot the furnace: which consiste iii the ability to draw ott the molten sine successively from one condenser after another and without suspending or materially diminishing the rate ot the reactitni.

lit is to be particularly noted that rin the present system the evolution ot the zine fumes will proceed according to the. rapidity with which heat units are supplied to the resistor: and by a proper control ot the in-put ot energy the temperature ot the evolved fumes and gases needs be but comparatively little higher than that required to produce the reaction. Therefore, as an ample temperature for the purpose is about 1300O C., ordinary re bricks may be used in the con struction of the reaction chamber which, 'under such conditions, will endure indefinitely, as has been thoroughly proven in act-ual practice.

-Obviously, as respects the charge, lthe idealA materials and condition would be chemically pure oXids-o-zinc (ZnO) and carbon (C) combined in the precise relatire proportions to produce a complete reaction, whereby all ot the materials would be evolved in the gaseous Jforms ot zinc (Zu) and orid-otcarhon (CU). Hencc there would be no residue whatever, and .so tar as is fknown, the tui-nace might thus operate coi'itinuously 'for months, or even years. ut. in actual practice. the use ot materials ot theoretical purity would probably be commercially prohibitive and their precise proportionment in successive charges might be troublesome to realize. However, perfect conditions are not necessary to gain the advantages ot this invention; for with oxidot-zinc and carbon (coke) ot ordinary coniinercial grade oi quality then the actual residuechietly in the form of sintered ashis a relatively negligible quant-ity over the period ot operation (weeks or months) which attainable; and even then the rt.- inoval ot a resistor-bed with any collected residue, and the substitution of a new resister, involves but a trilling delay and expense. Aigain, it matters little whether the two constituents ot the charge are ted to the furnace in precisely exact proportions; tor it there should be, on the one hand, an excess of oXid-of-zinc, this will make itself apparent by eating up carbon trom the resistor and will be denoted by a change in the electric resistance; the remedy for this 'would be to charge relatively more carbon. (En the other hand, it an excess of carbon is accumulated in the reaction chamber, this will also make itselt1 known by a Change in the normal resistance: the remedy for this would be to insert relatively more oXid-of- Zinc.

The exclusion ot' air troni the reaction zone oit the turnace chamber may be said to be absolute. Even the oxygen which may be entrained and. carried in with the charge is expelled and passes out ot .the reaction chamber through the feed openings in the cover betore it can reach the reaction Zone. rlhis also the case as to moisture and ap plies more or less to other volatilizable substances. Consequently, the dillirnlties ot condensation are by so much diminished and the carbon ot' the resistor and the terminals are neither deteriorated nor consumed.

The determining factor which limits the capacity ot' the herein described 'furnace is` taken a whole, 'the condenser. Hence. as a glance at the drawings will show, the ettorthas been to suppl y a condensing system which shall-have a high rate of output.- Yet it is feasible to still further amplify this element, as by the use ot deeper and longer condenser-,tubes and also, say, by superimcomposed substantially of carbon, carbon side Walls extending above the resistor, and condensers arranged to receive' unies and gases formed in the heat zone'of the ur nace, saidl condensers being filled 'With `car bon directly connected with the said carbon sides.

vaporous form, and to form oXid of carbon, and permitting the escape of said vaporous Zinc and oxid of carbon from the reducing zone; the furnace 'being successively recharged to maintain the height of the charge and the vaporous zinc and the o'Xid of carbon being allowed to escape as and when formed directly in the hot carbon, thereby enabling a continuous processto be carried zontal resistor, permeable side walls extending above the resistor, condensers arranged to receive the fumes formed in the heated zone adjacent to the resistor and means for eecting or controlling the heating con- -ditions of the condensers; the condensers being filled with carbon directly connected With the said permeable side Walls.

This specification signed and witnessed this 12th day of September A. D., 1911.

CHARLES V. THIERRY.

Signed in the presence of CLAUDIUS LUSSON, H. C. Coxn.

49. Anelect-rie furnace having a resistor composed substantially of carbon and carlined sides extending above the resistor, the said sides being in loosely agglomerated pieces.L v

10. An yelectric furnace having a horizontal carbon resistor, carbon sides extendingibove the resistor to receive and hold the charge therebetween, condensers Yleading from the resistor sides to permit the fumes and gases formed at the heatingvzone of the furnace to pass therethrough.

11. An electric furnace having a resistor 12. An electric furnace having a hori- 

